BACKGROUND OF THE INVENTION
The present invention relates to a transmission device for a wheelchair and, more particularly, to a transmission device for a wheelchair with a rehabilitation function.
A conventional chair capable of providing a rehabilitation function by using footrests for a patient to pedal generally uses a chain for transmission purposes. The chain requires lubrication by oil. During use of the wheelchair, if the clothes of a user of the wheelchair are close to the chain, the clothes could be soiled by the oil or even get caught by the chain, which is very dangerous.
BRIEF SUMMARY OF THE INVENTION
A wheelchair with a rehabilitation function according to the present invention includes a chair having a frame, two rear wheels, and two footrests. The two rear wheels are located on a rear end of the frame and are respectively located on two sides of the frame in a horizontal direction. The two footrests are located on a front end of the frame and are respectively located on two sides of the frame in the horizontal direction. Two transmission devices are connected to the frame and are associated with the two rear wheels and the two footrests. Each of the two transmission devices includes a housing, a driving shaft, a first transmission shaft, a second transmission shaft, a driven shaft, and a sliding member.
The driving shaft is mounted in the housing and is rotatable relative to the housing about a first axis. The driving shaft includes an end connected to one of the two rear wheels to permit synchronous rotation.
The first transmission shaft is mounted in the housing and is driven by the driving shaft to rotate relative to the housing about a second axis intersecting with the first axis. An end of the first transmission shaft opposite to the driving shaft includes a first reference face. The first transmission shaft includes a first engaging portion on the first reference face. The first engaging portion has non-circular cross sections perpendicular to the second axis.
The second transmission shaft is mounted in the housing and is rotatable relative to the housing about the second axis. The second transmission shaft is mounted to the end of the first transmission shaft opposite to the driving shaft. An end of the second transmission shaft adjacent to the first transmission shaft has a driving section.
The driven shaft is mounted in the housing and is driven by the second transmission shaft to rotate relative to the housing about a third axis parallel to the first axis and intersecting with the second axis. The driven shaft has an end connected to one of the footrests to permit synchronous rotation.
The sliding member is mounted around an outer periphery of the driving section to permit synchronous rotation. An end of the sliding member adjacent to the first transmission shaft includes a second engaging portion having non-circular cross sections perpendicular to the second axis. The second engaging portion removably engages with the first engaging portion. The sliding member is slideable along the second axis relative to the second transmission shaft between a transmission position and a release position. When the sliding member is in the transmission position, the second engaging portion engages with the first engaging portion, and the first transmission shaft and the sliding member rotate synchronously. When the sliding member is in the release position, the second engaging portion disengages from the first engaging portion, and the sliding member is not driven when the first transmission shaft rotates.
The present invention will become clearer in light of the following detailed description of illustrative embodiments of this invention described in connection with the drawings.
DESCRIPTION OF THE DRAWINGS
FIG. 1 is a perspective view of a wheelchair according to the present invention.
FIG. 2 is an exploded, perspective view of a transmission device of the wheelchair of FIG. 1.
FIG. 3 is a partly cross-sectioned side view of the wheelchair of FIG. 1.
FIG. 4 is a partly cross-sectioned view of a portion of the wheelchair of FIG. 1.
FIG. 5 is a partial, enlarged cross sectional view of the transmission device.
FIG. 6 is another partial, enlarged cross sectional view of the transmission device.
FIG. 7 is a partial, enlarged view illustrating a driving section of the transmission device.
FIG. 8 is a partly cross-sectioned view of a portion of the wheelchair, with a sliding member in a transmission position.
FIG. 9 is a view similar to FIG. 8, with a footrest moved.
FIG. 10 is a view similar to FIG. 5, with the sliding member in a release position.
FIG. 11 is a view similar to FIG. 6, with the sliding member in a release position.
FIG. 12 is a view similar to FIG. 10, with the sliding member in a locking position.
FIG. 13 is a view similar to FIG. 11, with the sliding member in the locking position.
DETAILED DESCRIPTION OF THE INVENTION
With reference to FIG. 1, a wheelchair 10 with a rehabilitation function according to the present invention includes a chair 20 and two transmission devices 30. The chair 20 includes a frame 21, two rear wheels 22, and two footrests 23. The rear wheels 22 are located on a rear end of the frame 21 and are respectively located on two sides of the frame 21 in a horizontal direction. The footrests 23 are located on a front end of the frame 21 and are respectively located on two sides of the frame 21 in the horizontal direction.
With reference to FIGS. 2-6, the transmission devices 30 are connected to the frame 21 and are located between the two rear wheels 22. The two transmission devices 30 are respectively associated with the two rear wheels 22 and the two footrests 23.
Each transmission device 30 includes a housing 31, a driving shaft 32, a first transmission shaft 33, a second transmission shaft 34, and a driven shaft 35. The housing 31 is a substantially Z-shaped hollow rod and includes a first portion 311, a second portion 312, a third portion 313, and a fourth portion 314. The second portion 312 is connected to the first portion 311. A protrusion 315 is formed on an outer surface of the second portion 312. The third portion 313 is connected to a side of the second portion 312 opposite to the first portion 311. A side of the third portion 313 adjacent to the second portion 312 includes a stepped compartment 316. The stepped compartment 316 has a bottom face facing the second portion 312 and includes an engaging projection 317 protruding from the bottom face. The fourth portion 314 is connected to a side of the third portion 313 opposite to the second portion 312.
The driving shaft 32 is mounted in the first portion 311 of the housing 31 and is rotatable relative to the housing 31 about a first axis L1. The driving shaft 32 extends along the first axis L1. An end of the driving shaft 32 is connected to one of the rear wheels 22 to permit synchronous rotation. A first bevel gear 321 is mounted to the other end of the driving shaft 32 opposite to the rear wheel 22 to permit synchronous rotation. The driving shaft 32 is substantially cylindrical.
The first transmission shaft 33 is mounted in the second portion 312 of the housing 31 and is driven by the driving shaft 32 to rotate about a second axis L2. An end of the first transmission shaft 33 adjacent to the driving shaft 32 is located in the first portion 311. The other end of the first transmission shaft 33 opposite to the driving shaft 32 extends beyond the second portion 312. The second axis L2 is orthogonal to the first axis L1. In this embodiment, the first and second axes L1 and L2 are perpendicular to each other. The first transmission shaft 33 extends along the second axis L2 A second bevel gear 331 is mounted to the end of the first transmission shaft 33 adjacent to the driving shaft 32 to permit synchronous rotation. The second bevel gear 331 meshes with the first bevel gear 321.
The end of the first transmission shaft 33 opposite to the driving shaft 32 includes a first reference face 332. The first transmission shaft 33 includes a first engaging portion 333 on the first reference face 332. The first engaging portion 333 is in the form of a groove and extends from the first reference face 332 towards the driving shaft 32 along the second axis L2. The first engaging portion 333 has non-circular cross sections perpendicular to the second axis L2. In this embodiment, the first engaging portion 333 extends through two sides of the first transmission shaft 33 in a diametric direction perpendicular to the second axis L2.
The end of the first transmission shaft 33 opposite to the driving shaft 32 includes a positioning groove 334. The positioning groove 334 is located in a center of the first transmission shaft 33 and extends towards the driving shaft 32 along the second axis L2. The positioning groove 334 has circular cross sections perpendicular to the second axis L2. In this embodiment, the positioning groove 334 is recessed in a side of the first engaging portion 333 adjacent to the driving shaft 32, and the first transmission shaft 33 is cylindrical.
With reference to FIG. 7, the second transmission shaft 34 is mounted in the third portion 313 of the housing 31 and is rotatable relative to the housing 31 about the second axis L2. The second transmission shaft 34 extends along the second axis L2. The second transmission shaft 34 is mounted to the end of the first transmission shaft 33 opposite to the driving shaft 32. An end of the second transmission shaft 34 adjacent to the first transmission shaft 33 has a driving section 341. The driving section 341 has non-circular cross sections perpendicular to the second axis L2. The driving section 341 of the second transmission shaft 34 is not in contact with the first transmission shaft 33. The driving section 341 includes an outer periphery having two arcuate faces 342 and two plan faces 343. The two arcuate faces 342 are diametrically opposed to each other and have an equal spacing to the second axis L2. Each plan face 343 is connected between the two arcuate faces 342. The two plan faces 343 are opposite and parallel to each other.
The end of the second transmission shaft 34 adjacent to the first transmission shaft 33 has a positioning section 344. The positioning section 344 is located in the center of the second transmission shaft 34 and is located adjacent to a side of the driving section 341 adjacent to the first transmission shaft 33. The driving section 341 has circular cross sections perpendicular to the second axis L2. The positioning section 344 of the second transmission shaft 34 is inserted into the positioning groove 334 of the first transmission shaft 33. A third bevel gear 345 is mounted to the end of the second transmission shaft 34 opposite to the first transmission shaft 33 to permit synchronous rotation.
The driven shaft 35 is mounted in the fourth portion 314 of the housing 31 and is rotatable relative to the housing 31 about a third axis L3. The third axis L3 is parallel to the first axis L1 and is orthogonal to the second axis L2. In this embodiment, the second and third axes L2 and L3 are perpendicular to each other, and the first and third axes L1 and L3 are on the same plane. The driven shaft 35 extends along the third axis L3. An end of the driven shaft 35 is connected to one of the footrests 23 to permit synchronous rotation. A fourth bevel gear 351 is mounted to the other end of the driven shaft 35 opposite to the footrest 23 to permit synchronous rotation. The fourth bevel gear 351 meshes with the third gear 345. The driven shaft 35 is cylindrical.
Each transmission device 30 further includes a sliding member 36, an operating rod 37, an elastic element 38, and a spring 39. The sliding member 36 is mounted to an outer periphery of the second transmission shaft 34 to permit synchronous rotation. The sliding member 36 is received in the stepped compartment 316. The sliding member 36 is slideable along the second axis L2 relative to the second transmission shaft 34 between a transmission position, a release position, and a locking position. The sliding member 36 includes an insertion hole 361 extending along the second axis L2. The insertion hole 361 has non-circular cross sections perpendicular to the second axis L2 and corresponding to the cross sections of the driving section 341. The driving section 341 is inserted into the insertion hole 361.
An end of the sliding member 36 adjacent to the first transmission shaft 33 has a second engaging portion 362. The second engaging portion 362 is in the form of a protrusion and extends towards the first transmission shaft 33 along the second axis L2. The second engaging portion 362 has non-circular cross sections perpendicular to the second axis L2. In this embodiment, the second engaging portion 362 extends in a diametric direction perpendicular to the second axis L2 to two sides of the second transmission shaft 34. The second engaging portion 362 is removably engaged with the first engaging portion 333.
An end of the sliding member 36 opposite to the first transmission shaft 33 includes an engaging groove 363. The engaging groove 363 extends towards the first transmission shaft 33 along the second axis L2. An outer periphery of the sliding member 36 is stepped and includes an abutment face 364 extending in a radial direction perpendicular to the second axis L2. The abutment face 364 faces the first transmission shaft 33.
An intermediate portion between two ends of the operating rod 37 is pivotably connected to the third portion 313 of the housing 31. One of the two ends of the operating rod 37 is mounted in the compartment 316 of the housing 31. The other end of the operating rod 37 extends beyond the housing 31. The end of the operating rod 37 in the house 31 abuts the abutment face 364 of the sliding member 36. The end of the operating rod 37 adjacent to the sliding member 36 is U-shaped and is seated on two sides of the sliding member 36 diametrically opposite to each other. The end of the operating rod 37 opposite to the sliding member 36 is aligned with the protrusion 315.
The elastic element 38 is mounted around the second transmission shaft 34. An end of the elastic element 38 abuts the end of the sliding member 36 opposite to the first transmission shaft 33. The other end of the elastic element 38 abuts the housing 31. The elastic element 38 biases the sliding member 36 towards the first transmission shaft 33. Two ends of the spring 39 abut the protrusion 315 and the operating rod 37.
FIGS. 8 and 9 show the sliding member 36 in the transmission position. When a care taker intends to change the position of the sliding member 36, a controller 90 is operated to pull a cable 91 to actuate the operating rod 37, which, in turn, pushes and, thus, moves the sliding member 36. When the pulling force of the cable 91 is released, the operating rod 37 is moved back to its original position under the action of the spring 39, and the sliding member 36 is pushed back to the transmission position.
When the sliding member 36 is in the transmission position, the second engaging portion 362 engages with the first engaging portion 333, and the first transmission shaft 33 and the sliding member 36 rotate synchronously. When the care taker pushes the chair 20 and, thus, rotates the rear wheels 22, the footrests 23 are driven by the driven shafts 35 to rotate relative to the chair 20. Since the feet of the sitter rest on the footrests 23, the footrests 23 can carry the feet and the legs of the sitter to move, achieving a rehabilitation effect.
FIGS. 10 and 11 show the sliding member 36 in the release position. The second engaging portion of the sliding member 36 disengages from the first engaging portion 333, such that the first transmission shaft 33 cannot drive the sliding member 36 to rotate. The second transmission shaft 34 rotates freely relative to the housing 31. In this case, when the care taker pushes the chair 20, the footrests 23 do not move together with the rear wheels 22 and can sway freely relative to the chair 20.
FIGS. 12 and 13 show the sliding member 36 in the locking position. The engaging protrusion 317 of the housing 31 engages with the engaging groove 363 of the sliding member 36, such that the second transmission shaft 34 cannot rotate relative to the housing 31. In this case, when the care taker pushes the chair 20, the footrests 23 cannot sway relative to the chair 20.
Although specific embodiments have been illustrated and described, numerous modifications and variations are still possible without departing from the scope of the invention. The scope of the invention is limited by the accompanying claims.